IPCC and the Politization of Climate Science

Yesterday, as I was running around trying to better understand the "junk science" debates, I ran into Kerry Emanuel's Phaeton’s Reins: The human hand in climate change, Boston Review, January/February 2007. Long fascinated with complexity theory, I was captured by Emanuel's contrast of "stability myths" to complexity, chaos, complex systems, dynamics, feedback loops, etc., and to the modeling of complex systems—in this case climate- and weather-change modeling.

Toward the end of the article, Emanuel turns his attention to the contemporary dilemma of what some call "the science wars", wars of words that are really more the stuff of media, politics, and social activism than of science. Here is a snip (with some red highlights from me):

Science, politics, and the media
Science proceeds by continually testing and discarding or refining hypotheses, a process greatly aided by the naturally skeptical disposition of scientists. We are, most of us, driven by a passion to understand nature, but that means being dispassionate about pet ideas. Partisanship—whatever its source—is likely to be detected by our colleagues and to yield a loss of credibility, the true stock of the trade. We share a faith—justified by experience—that at the end of the day, there is a truth to be found, and those who cling for emotional reasons to wrong ideas will be judged by history accordingly, whereas those who see it early will be regarded as visionaries.

The evolution of the scientific debate about anthropogenic climate change illustrates both the value of skepticism and the pitfalls of partisanship. Although the notion that fossil-fuel combustion might increase CO2 and alter climate originated in the 19th century, general awareness of the issue dates to a National Academy of Sciences report in 1979 that warned that doubling CO2 content might lead to a three-to-eight-degree increase in global average temperature. Then, in 1988, James Hansen, the director of NASA’s Goddard Institute for Space Studies, set off a firestorm of controversy by testifying before Congress that he was virtually certain that a global-warming signal had emerged from the background climate variability. At that time, less was known about natural climate variability before the beginning of systematic instrumental records in the nineteenth century, and only a handful of global climate simulations had been performed. Most scientists were deeply skeptical of Hansen’s claims; I certainly was. It is important to interpret the word “skeptical” literally here: it was not that we were sure of the opposite, merely that we thought the jury was out.

At roughly this time, radical environmental groups and a handful of scientists influenced by them leapt into the fray with rather obvious ulterior motives. This jump-started the politicization of the issue, and conservative groups, financed by auto makers and big oil, responded with counterattacks. This also marked the onset of an interesting and disturbing phenomenon that continues to this day. A very small number of climate scientists adopted dogmatic positions and in so doing lost credibility among the vast majority who remained committed to an unbiased search for answers. On the left, an argument emerged urging fellow scientists to deliberately exaggerate their findings so as to galvanize an apathetic public, an idea that, fortunately, failed in the scientific arena but which took root in Hollywood, culminating in the 2004 release of The Day After Tomorrow. On the right, the search began for negative feedbacks that would counter increasing greenhouse gases: imaginative ideas emerged, but they have largely failed the acid test of comparison to observations. But as the dogmatists grew increasingly alienated from the scientific mainstream, they were embraced by political groups and journalists, who thrust them into the limelight. This produced a gross distortion in the public perception of the scientific debate. Ever eager for the drama of competing dogmas, the media largely ignored mainstream scientists whose hesitations did not make good copy. As the global-warming signal continues to emerge, this soap opera is kept alive by a dwindling number of deniers constantly tapped for interviews by journalists who pretend to look for balance.

While the American public has been misinformed by a media obsessed with sensational debate, climate scientists developed a way forward that helps them to compare notes and test one another’s ideas and also creates a valuable communication channel. Called the Intergovernmental Panel on Climate Change, or IPCC, it produces a detailed summary of the state of the science every four years, with the next one due out in February 2007. Although far from perfect, the IPCC involves serious climate scientists from many countries and has largely withstood political attack and influence.

The IPCC reports are fairly candid about what we collectively know and where the uncertainties probably lie. In the first category are findings that are not in dispute, not even by les refusards:

• Concentrations of the greenhouse gases carbon dioxide, methane, ozone, and nitrous oxide are increasing owing to fossil-fuel consumption and biomass burning. Carbon dioxide has increased from its pre-industrial levelsl of about 280 parts per million (ppmv) to about 380 ppmv today, an increase of about 35 percent. From ice-core records, it is evident that present levels of CO2 exceed those experienced by the planet at any time over at least the past 650,000 years.
• Concentrations of certain anthropogenic aerosols have also increased owing to industrial activity.
• The earth’s average surface temperature has increased by about 1.2°F in the past century, with most of the increase occurring from about 1920 to 1950, and again beginning around 1975. The year 2005 was the warmest in the instrumental record.
• Sea level has risen by about 2.7 inches over the past 40 years; of this, a little over an inch occurred during the past decade.
• The annual mean geographical extent of arctic sea ice has decreased by 15 to 20 percent since satellite measurements of this began in 1978.

In the second category are findings that most climate scientists agree with but are disputed by some:

• The global mean temperature is now greater than at any time in at least the past 500 to 1,000 years.
• Most of the global mean temperature variability is caused by four factors: variability of solar output, major volcanic eruptions, and anthropogenic sulfate aerosols and greenhouse gases.
• The dramatic rise in global mean temperature in the past 30 years is owing primarily to increasing greenhouse-gas concentrations and a leveling off or slight decline in sulfate aerosols.
• Unless measures are taken to reduce greenhouse-gas production, global mean temperature will continue to increase, about 2.5 to 9°F over the next century, depending on uncertainties and how much greenhouse gas is produced.
• As a result of the thermal expansion of sea water and the melting of polar ice caps, sea level will increase six to 16 inches over the next century, though the increase could be larger if large continental ice sheets become unstable.
• Rainfall will continue to become concentrated in increasingly heavy but less frequent events.
• The incidence, intensity, and duration of both floods and drought will increase.
• The intensity of hurricanes will continue to increase, though their frequency may dwindle.

All these projections depend, of course, on how much greenhouse gas is added to the atmosphere over the next century, and even if we could be certain about the changes, estimating their net effect on humanity is an enormously complex undertaking, pitting uncertain estimates of costs and benefits against the costs of curtailing greenhouse-gas emissions. But we are by no means certain about what kind of changes are in store, and we must be wary of climate surprises. Even if we believed that the projected climate changes would be mostly beneficial, we might be inclined to make sacrifices as an insurance policy against potentially harmful surprises. …